Submission #1519668

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Source Code Expand

#include <cstdio>

#define REP(i,n) for (int i=0;i<(n);i++)
#define MAX_N 100000

int par[MAX_N], rank[MAX_N];
int n, m;

void init(){
  REP(i, n){
    par[i] = i;
  }
}

int find(int x){
  if(par[x] == x)
    return x;

  return par[x] = find(par[x]);
}

void unite(int x, int y){
  x = find(x);
  y = find(y);

  if(x == y)
    return;

  if(rank[x] > rank[y]){
    par[y] = x;
  }else{
    par[x] = y;
    if(rank[x] == rank[y]){
      rank[y]++;
    }
  }
}

bool same(int x, int y){
  return find(x) == find(y);
}

int main(){
  scanf("%d %d", &n, &m);
  init();

  REP(i, m){
    int a, b;
    scanf("%d %d", &a, &b);
    a--; b--;
    unite(a, b);
  }


  int ans = 0;
  REP(i, n){
    if(!same(0, i)){
      ans++;
      unite(0, i);
    }
  }

  printf("%d\n", ans);

  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:44:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &n, &m);
                         ^
./Main.cpp:49:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &a, &b);
                           ^

Judge Result